Here is my problem, I tested my glow plug today, 0.5 ohms on each one. Tested the power(pin 11), ground(pin 7) on the glow plug module, 12 volts and good ground. Tested continuity for the GP module signal and control between the ECM and GP module, 0.5 ohms. Tested voltage going to the GP, 2.5 volts for about 1-2 secondes and back to 0 volts after ?!?! WTF!!! It should be at least 5 volts (I have the 5 volts Hot tune programming from GDE) and with the temperature we have, 4 degree celsius (40 fahrenheit), it should stay ON longer than that. I changed the GP module and get the same result.

Did someone get the same problem? The ECM get is temperature signal from were? Can the signal or sensor be broken? Can the ECM have a problem just for that?

I need some help. I have a spare ECM, can I just reload my stock tune and change it? Will I be able to to load my hot tune back on the new ECM after? Will the ECM even work, different serial number?

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06 Jeep Liberty CRD limited, GDE hot tune, Samco hoses, V6 air box mod, AFE air filter, Carter in-tank fuel pump, model 101 thermostat, EGR delete kit with glow plug, 205 000 km;

You are using the 5v glow plugs, correct?

What is the problem? Why did you feel the need to start testing?

I seriously doubt that the problem it with the ECM or the tune.
Most likely, its your method of testing thats giving you a false voltage reading. Or its your meter.
The voltage to the glow plugs is actually 12volts. But the ECM pulses the voltage so that it averages out to be 5volt (or 7 volts).

ECM uses the coolant temperature sensor for determining ON time for the glow plugs.
The plugs heat up quick. 1-2 seconds is more than enough time.
If you disconnect the temp sensor you can increase the ON time. But then the engine wont run right.

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U.S. Army Retired

My problem is that the jeep won't start at 0 degree celsius unless it is plugged in and 1-2 seconds obviously is not enough. Even if the ECM is pulsing 12 volts to get 5 volts, I should be able to read the voltage for more than 1-2 secondes.

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06 Jeep Liberty CRD limited, GDE hot tune, Samco hoses, V6 air box mod, AFE air filter, Carter in-tank fuel pump, model 101 thermostat, EGR delete kit with glow plug, 205 000 km;

Only the OEM 7v ceramics give good cold starts. The reason you aren't seeing 5v with you multi meter is because the ECM pulses the glow plugs. You need an oscilloscope to see the voltage peaks.

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SOLD - 2006 Jeep Liberty CRD Limited
Gen2 Fuel Head - Magnaflow Exhaust - Ram transmission swap - In-Tank Lift Pump
Moab Wheels - 245/75/R16 LR E Cooper Discoverer AT3 Tires - OME Lift 790/90009 948/60069 - Etecno Glow Plugs - V6 Airbox
Pic of my Jeep!

OK for the oscilloscope, let's just say it has the right voltage, how come it just stays ON for 1-2 secondes when it should stay ON for longer? Even thought I am not reading the right voltage, I am still reading something and that something only stay ON for 2 secondes that is why I am thinking there is something wrong with my GP system. In the 2006-km-sm book that I have, it has 6000 pages, at pages 968, it says that the pre-heat cycle should be 21 secondes at -10 degree celsius, it stays ON for 16 secondes at 70 degree celsius.

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06 Jeep Liberty CRD limited, GDE hot tune, Samco hoses, V6 air box mod, AFE air filter, Carter in-tank fuel pump, model 101 thermostat, EGR delete kit with glow plug, 205 000 km;

Mine has always just flashed upon startup. The only time my glow plug light stays on is during below zero starting and not plugged in. Even then, the wait to start light is only on for approx two seconds.

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2020 Ram 1500 CC Ecodiesel Limited
1995 Dodge Ram 2500 4x4, 5.9 Cummins, 47RH, Reg Cab
2005 Liberty CRD,fixed the rockers and a couple more things,GDE Hot tune,Weeks Stage 1 and 2 EGR delete,Hot Diesel solutions Tstat assembly(wonderful heat!), ARP studs, OME 1.5" lift.....thanks Seth! (Sold)
2006 Liberty CRD....The Moose Hit

Yes the light will stay ON for only a few second, but the GP will stay ON for longer even after the engine is running. I will be doing more test today. It is -15 degree celsius outside and the jeep is not plugged in, the GP should stay on a lot longer at that temperature.

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06 Jeep Liberty CRD limited, GDE hot tune, Samco hoses, V6 air box mod, AFE air filter, Carter in-tank fuel pump, model 101 thermostat, EGR delete kit with glow plug, 205 000 km;

See 06 FSM page section 8I beginning on page 8I-21 for testing and operation of glow plugs. If you lack the FSM you can download a copy at http://colorado4wheel.com/manuals/Jeep/KJ/

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

Thank you papa indigo, that is the book I have been using. I did more testing this morning. -11 degree celsius, tested the voltage to see how long the GP were staying ON, they stayed on for at least 5 secondes after the all the chimes went off, but still only have 2.5 volts, tried it, didn't want to start. So I decided to install my original software just to see if there was a change, still the GP stayed ON for 5 secondes after the chimes went off, but this time I had 5 volts the whole time. Can it be the programming of the GDE? I have both the 5 and 7 volts programming, I will install the 7 volts now and see if there is a change. And by the way, I tried to start it with the original software and it started.

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06 Jeep Liberty CRD limited, GDE hot tune, Samco hoses, V6 air box mod, AFE air filter, Carter in-tank fuel pump, model 101 thermostat, EGR delete kit with glow plug, 205 000 km;

So, the original programming was 7 volt glow plugs?
And then it started with the 5 volt glow plugs installed while using the 7 volt programming?

7 volt programming with 5 volt plugs wills cause the plugs to run hotter than they should.

What about your intake elbow with heater plug? Is it not working?

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U.S. Army Retired

I just install the GDE hot tune 7 volts programming and only had 3.5 volts for the same amount of time. I have both 5 and 7 volts programming from GDE and they both only have half the voltage they are supposed to be running. The original programming, which is supposed to be 7 volts is giving me(measured with voltmeter) 5 volts and it is the only programming that will start the engine at -11 degree celsius right now. I know the & volts programming will hurt the 5 volts GP but at least the engine will start. The intake elbow help a little bit but not that much. I will send an email to Keith to see what he thinks of the whole thing.

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06 Jeep Liberty CRD limited, GDE hot tune, Samco hoses, V6 air box mod, AFE air filter, Carter in-tank fuel pump, model 101 thermostat, EGR delete kit with glow plug, 205 000 km;

Was there any resolution? I'm going though nearly identical troubles and have resorted to plugging in (with a battery warmer and charger as well)